1. Field of the Invention
The invention relates to the production of dehydrated intact cooked potato cells, i.e. potato granules. Further, the invention relates to a single-pass, continuous process not requiring the addback of the final product to the starting materials as required in prior art potato granule processes.
2. Description of the Prior Art
There are numerous disclosures in the prior art for processes to produce by a direct process dehydrated potato pieces capable of reconstitution to a mashed potato.
Great Britain Pat. No. 542,125 discloses a process wherein mashed potatoes are dried at a temperature of 50.degree.-60.degree.C. for two hours to reach a moisture content of 40 to 60%. The partially dried mash is then compressed and conditioned for 6 to 24 hours, after which it is divided by rubbing through a sieve, and the divided pieces are then dried to completion.
U.S. Pat. No. 2,750,295 discloses a process in which mashed potatoes are mixed with ethyl alcohol and 60% of the moisture is removed by distillation. Additional alcohol is mixed with the partially dried potatoes to remove an additional 35% of the water, and after filtration, the unicellular granules are dried conventionally. This process is too costly and leaves an undesirable residual flavor.
Also there are many prior art processes based on the "freeze-squeeze" approach in which mashed potatoes are frozen; thawed; and dewatered to produce a friable damp powder which can be dried conventionally. However, such processes are not satisfactory because of economic reasons coupled with unacceptably large losses of solids and nutrients and resulting sandy texture.
Great Britain Pat. No. 740,711 to Templeton discloses a non-addback process for making dehydrated potato powder except that addback is initially used during start-up. Templeton adds cooked potatoes having up to 60% moisture to the inlet end of a three trough mixer-evaporator. Each trough is surrounded by a steam jacket to keep the product at about 50.degree.C. maximum. Countercurrent air is blown over the product to evaporate the water as the product progresses through the mixer. At the outlet end a moist powder is discharged having below 30% moisture which is then final dried. The process is either a batch process or can be run continuously by adjusting the rate of input with the rate of output so that a certain level is maintained in the mixer. There is no disclosure of the use of monoglycerides nor is there a disclosure that the powder is granulated without excessive damage during mixing and entrained by the air flow.
U.S. Pat. No. 3,133,797 to Pierson discloses a non-addback process for dehydrating potatoes in which the cooked potatoes are mechanically forced by a roller through screen openings separating the mash into aggregates and are then blown off of the screen by an air blast. The particles fall through a dehydrator counter-current to a warm air flow and are then finish dried. The end product is a mixture of granules and powder. A similar process is disclosed in U.S. Pat. No. 3,517,716 to Carlsen which includes additional baffle means and countercurrent air flow means to retard the free fall of the comminuted particles through the dryer and permit adequate drying thereof. Neither of these processes disclose the use of monoglycerides nor the granulation of the moist mash by passing it through the dryer and entraining the granulated particles in the air flow to remove them from the system.
U.S. Pat. No. 3,009,817 to Hendel discloses a non-addback process for making dehydrated potato granules. Raw potatoes are washed, peeled, trimmed, cut, and dipped in sodium bisulphite solution and cooked. The cooked potatoes are mashed, blended with optional additives which include edible dispersing agents such as monoglyceryl esters of long chain fatty acids to increase the ability to absorb water and to reduce stickiness, and then conditioned by cooling for several hours either at room temperature or for shorter periods at down to sub-freezing temperatures. The conditioned, cooked potatoes are then granulated by subdividing the mash into single cells without rupturing the cells by gently mixing in a granulator while subjecting the mix to a hot air stream to reduce moisture. Thereafter, the temperature and velocity of the air is increased and the granulated particles are entrained by the air stream and carried into a collector and then finally dried. The process is long, requiring as a minimum 2 to 3 hours from the time the conditioning step begins. Hendel teaches the elimination of or shortening the duration of his conditioning step but only in a process where portions of the final product are added back to the starting materials and even then a cooling step is required. See also, U.S. Pat. No. 3,009,816 to Hendel for a generally similar disclosure but teaching the addition of a 1 - 4 hour soaking step prior to cooking in order to increase the water absorption characteristics of the dehydrated granules.
Applicants have found, through the proper use of monoglycerides to coat the individual intact cooked potato cells, a unique process by which Hendel's conditioning step can be eliminated without the need to use either a cooling step or the step of adding back final product to the starting materials and applicants achieve improved water absorption characteristics over prior art granules without a soaking step. Applicants' process is quick and effective and a distinct improvement over Hendel's teachings.
Cooked potato cells are extremely fragile and if ruptured during processing, the end products are too rubbery or sticky to be utilized in making mealy mashed potatoes. This accounts for the failure of prior art single-pass potato granules processes to make a product of acceptable quality. In contrast, the product of this invention has a more natural, freshly cooked potato flavor. The product is not subjected to repeated handling and heating and does not require the protective additives necessary in some prior art processes. The texture is mealy when reconstituted in contrast to stickiness or a sandy quality characteristic of prior art products. In addition, the product of the invention has improved cold water absorption qualities and is especially desirable in formulation of fabricated potato snack products such as those described in U.S. Pat. Nos. 3,539,356 and 3,576,647.